Sound apparatus



Feb. 17, 1931. w. T. PLuM. .JR 1,792,603

soUND APPARATUS Filed Jan. 5, 1930 IIIIIIIIIIIIIIIIIII/IIIII I IN V EN TOR. GWWV Mam M ATTORNEYS.

Patented Feb. 17, 1931 UNITED sTArEs PATENT OFFICE;

SOUND APPARATS Application` fi-leiV January 6, 1930. Serial No. 418,727.

This invention. is directed to 'an improvedf method and apparatus for obtaining certain deslred results in sound, andhas for one of its objects the provision of a method and apparatus Whereby sound Waves emanating from a central source may be seleetively intensified and/or dampedj as desired, therebyV effecting an increase in intensity of certain soundand/ or a d'ecrease in. others Whereby in an enclosure, such as an auditorium, for example, the soundsfrom a main source, such as a stage, may be heard With the correct and desired intensity throughout the entire enclosure.

It Will be obvious from the description which folloWs that a great variety of eflects may be prod'ucedl by myimproved method and apparatus, but in order that any invention may be clearly understood shall confine the description thereof to a method and apparatus as applied-in connection with sound production within an enclosure or Chamber, such as an auditorium.

In such enclosure it has been impossible prior to my invention to obtain correct results throughout the auditorium so far as proper reception of the sounds from a central source, such as a stage, are concerned due to echo effects, absorption effects and directional effects which are inherent in the structure of the enclosure.

Various means have been tried to overcome these effects mainly directed, however, to the placing' of some sound absorbing medium at those places or zones where the sound is other- Wise intensified, or sound reflecting mediums at those places or zones Where the sound is otherwise absorbed or damped.

My invention goes far beyond this, however, in that the sound absorbing and/ or sound refiecting mediums. heretofore employed absorb or reflect, as the case may be, to a certain degree all sounds coming. in contact With them so that What isl gained in absorbingV or refiecting certain sounds islost b absorbing or reflecting others as Well. Di

ficulty has ben experienced With these. prior devices with directional eflects which are also objectionable.

In the practice of my invention I deliberately select the sound Waves which are toV 'be damped or the amplitudes of which areto.

be increased without, however, alteringwhen my invention is in operation the amplitude of the remaining Waves. Inithis Way true effects, may be obtained throughout the entire enclosure or auditorium.

More specifically, my invention consistsin the employment of sound intensifying means and/or sound damping means, the characterand location of these means beingV preselected and: dependent upon the results desired.`

For example, in an auditorium Where owing to the construction thereof echo effects are pronounced, it has been customary, as. above pointed out, to employ sound absorbing. mediums, such as draperies, nets or other' means at that location. As also pointedvout above these mediums are not satisfactory in. that they absorb to a detrimental degree all sound striking them, being most absorbent ofcourse to those sounds having frequencies which are most readi'ly damped by the medium employed. This characteristc Will naturally vary depending upon the type ofv ab.- sorbing mediums empl'oyed.

Asdistinguished from such an expediency I place a damping means at such. a location which could, for example, take theV form of: a tuned resonator tube, this tube being de,- signed so as to be responsive only to the Wave to be damped. It Will also. be placed in a. predetermined location With respect not only to the central sound source but also With respect to the sound reflecting source, being so.v located as to be in phase, With, the original sound wave but out of phase With the reflected soundV Wave. As a consequence the resonato'r Will be caused to vibrateby the original sound. Wave being in phase With it, thereby to damp the reflected. Wave With, Whichit is out of phase.

In those locations where the sound is naturally absorbed oWing to the construction of theenclosure I propose to place, sound intensifying means. This means may take. the form of a resonator tube whichV is tuned and responsive only to those sound Waves Which are to be intensified and Will be located, as before, in phase WithV the originalsound'and .at the sameitime inphase With the sound Waves of the same theoretical frequency reflected by the sound absorbing area under consideration.

At other locations in the auditorium, for example, beneath the balconies, difficulty has been experienced heretofore in vabsorprtion of soundsby the balcony structure so that sounds are barely audible at that part of the auditorium lying beneath the rearof the balcony. Thisv balcony structure of courseabsorbs sound Waves of all frequencies to some degree and in this connection I propose to place a bankof tuned resonator tubes at or adjacent the edge of the balcony, these tubes being so located with respect to the central sound source as'to be in phase with the Waves emanating'therefrom. In this way I obtain a reinforcement of all 'soundsreaching the balcony and a resultant increase .in intensity of all sounds traveling to the back of the auditorium beneath the balcony.

In the accompanying drawing's 'wherein Il have illustrated my invention diagrammatically Fig. l is a plan view and Fig. 2 a

section on the line 2--2 of Fig. 1. A designates an enclosure such as an auditorium in which sounds are to be produced from a central sound source or main sound source shown at B and which may be in the nature of loud Speakers.v g This centralor main sound source is vlocated on the stage O.

lDdesignates a balcony, While E designatesf a column' or post along one wall of the audi'- torium, and F designates a. room along another wall. `The balcony D, post or column E and room F are shown merely as illustrative of sound absorbing means and sound reflecting means which effect the proper'distribution of sound from the main source Br throughout 'the enclosure. As mentioned above in the general discussion ofmy invention, the effect of the balcony'D is to absorb to a detrimental degree sounds produced by the main or central source B so as torender it extremely difiicult for these sounds to be audible on the lower floor of the auditorium beneath the balcony, particularly at the rearv of the balcony.V To overcome this defect I place at or adjacent the front edge of the bal'- copy aseries of resona-tor tubes designated G, as many as found necessary. These resonators are tuned, each resonator having its own y natural period of vibration and their effect is'to intensify the sound Waves having the same frequency as the natural period'of vibration of the tubes.

It is to be understood that each tube will be located in phase With the Waves corresponding in vfrequency to the natural period of vibration of the tube. It will be appreciated that: the effect of a bank of these tubeswill be to'intensify the sounds emanating from the sound source B' With a resultant increase in the intensity of the sounds traveling into the space beneath the balcony.

The post or, column E has been shown as an example of another type of sound absorbing medium and in order that' the efiects resulting from the absorption of sounds by this column may be overcome I place in proximity to the column a tunedrtube or tubes I-I, this tube being tuned and designed with reference to the frequency of the Waves which are absorbed by column E, and the'tube is so located With respect to the column E' as to be in phase with the wave or Waves which are most readily absorbed by the column, and at the same time in phase With the Waves which theoretically are reflected by the column. In this way the absorptive effect ,of the column isefectually overcome. w

. The room F has been shown merely as illustrative of a construction tending to produce echo orreflective effects in the auditorium and in order that these'elfects may be overcome I place adjacent this room one or side of the room F. In` this way the tube or,

tubes Ifwill be set into vibration but out of 4phase With the'waves reflected by the wall J to damp the same and thus eliminate the reflection or' echo efiect. a

It will be understood that'my invention may be' practiced in a variety of ways without departing'from the spirit and scope thereof, and that the drawing` is merely illustrative and not definitive.

What I claimfiszr s `1. In sound production the method of reducing sound absorbing efiects which comprises placing tuned resonators in proximity to the sound 'absorbing medium, said resonators being so placed as to be'in phase With sound Waves corresponding in frequency to the frequency for which they are designed and in phase With Waves of the same frequency refiected from the absorbing medium.

2. In the production of sound within a Chamber the method of reducing echo efiects which method comprises placing tuned resonatorsin proximity to the structure producing the echo, said resonators being in phase with Vsoundwaves of the same vfrequency as the natural period of the resonators emanating from a sound sourceandv out of phase with `Waves of-tlae same frequency refiected from the echo Vproducing structure. o

3. In the production of sound within an auditorium themethod of improving the'disl llO ing to the natural period of vibration of the resonators, and in such position With respect to the auditorium structure that some of said resonators Will be in phase and others out of phase With sound Waves reflected by certain preselected areas of the auditorium structure, so that in some instances a reinforcement of the sound Waves and in others a damping of the sound Waves Will be effected.

4. In the production of sound the method which comprises the placement of a plurality of tuned resonators responsive to a sound source in operative relation With the sound source at predetermined distances therefrom to neutralize by phase difference the sound Waves that are reflected from certain surfaces in the path of the sounds from the sound source.

5. In the production of sound the method Which comprises placing a plurality of tuned resonators responsive to a sound sourceV in operative relation With the sound source and at predetermined distances therefrom to reinforce by similar phase coincidence the Waves that are reflected from certain surfaces in the path of sounds from the source.

6. In the production of sound the method which comprises placing a plurality of tuned resonators of predetermined frequency response in operative relation With the sound source at predetermined distances therefrom, thereby to place certain other frequencies of the Waves from the source by interference of Waves from the resonators and Waves from the sound source.

7. In the production of sound the method Which comprises placing a predetermined number of tuned resonators responsive to sounds from a sound source in operative relation to the sound source and at predetermined distances therefrom, said resonators being also located at predetermined distances with respect to refiection of sounds from said source from disturbing areas in the path of the sound Wave emanating from the sound source, thereby to reinforce the Waves refiected from said disturbing areas by coincidence in phase of the resonators and the reflected Waves.

8. In the production of sound the method Which comprises placing a plurality of tuned resonators in operative relation to and at predetermined distances from a sound source and also at predetermined distances With respect to sounds reflected from disturbing areas located in the path of sound Waves emanating` from the sound source, thereby to neutralize the Waves refiected from the disturbing areas by diferences in phase of the resonators and the reflected Waves.

9. In sound production the combination of a sound source, an absorbing area in the path of sound Waves emanating from said source, and resonators intermediate the sound source and absorhing area and tuned to and in phase llO 

